Methodology for recycling ru and ru-alloy deposition targets &amp; targets made of recycled ru and ru-based alloy powders

ABSTRACT

A recycled deposition source is ruthenium (Ru) or Ru-based alloy material in the form of a powder material having a size not greater than a 325 mesh size and having an average tap density greater than about 5 gm/cm 3 . The power material may be non-porous and not agglomerated The recycled deposition source may have less than about 500 ppm of iron and less than about 500 ppm of oxygen. The recycled deposition source may be a recycled Ru or RuCr deposition source, where the recycled Ru or RuCr deposition source has a density comparable to a density of a Ru or RuCr deposition source fabricated from virgin Ru or RuCr powder material, and has a hardness greater than a hardness of a Ru or RuCr deposition source fabricated from virgin Ru or RuCr powder material. The recycled deposition source may be in the form of a sputtering target.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/927,325 entitled “Methodology For Recycling Ru and Ru-AlloyDeposition Targets & Targets Made of Recycled Ru and Ru-Based AlloyPowders,” filed on Oct. 29, 2007, which is hereby incorporated byreference in its entirety for all purposes.

FIELD

The present disclosure generally relates to methodology for recyclingruthenium (Ru) and Ru-based alloy materials and to products made fromthe recycled Ru and Ru-based alloy materials. The disclosure hasparticular utility in recycling of Ru and Ru-based alloy depositiontargets, e.g., sputtering targets, and to targets made from powders ofthe recycled Ru and Ru-based alloy materials.

BACKGROUND

Ruthenium and ruthenium-based alloy materials are increasingly utilizedin the manufacture of a number of advanced technology products, e.g., ascoupling layers in high performance, high areal recording densityanti-ferromagnetically coupled (“AFC”) magnetic recording media and asadhesion/seed layers in copper-based “back-end” metallization systems ofhigh integration density semiconductor integrated circuit (“IC”)devices. Such layers are typically formed by sputter depositionprocessing, e.g., magnetron sputtering, utilizing Ru or Ru-based alloytargets. However, use of the sputtering targets in a given applicationis limited due to consumption of the target over time, primarily becauseof concern of target penetration due to irregular or uneven (i.e.,local) sputtering over the target surface. Economic considerationsarising from the high cost of Ru and Ru-based alloys dictate recovery ofthese materials from spent targets.

Conventional methodology for recycling Ru and Ru-based alloy materials,e.g., from spent targets, typically involves chemical refiningprocessing. However, such chemical refining processing incurs a numberof disadvantages, including:

-   -   extremely long processing intervals, e.g., on the order of about        12 weeks;    -   high cost;    -   porous and highly agglomerated nature of the recycled product,        rendering it undesirable for use in subsequent fabrication of        new targets; and    -   relatively low tap density of the recycled product powder, i.e.,        about 4.0 gm/cc on average, necessitating increase in the        packing density prior to target formation.

In view of the foregoing, there exists a clear need for improved, morecost effective methodology for recycling Ru and Ru-based alloy materialsfor facilitating re-use thereof, e.g., as in the manufacture of Ru andRu-based deposition targets (such as sputtering targets) using recycledmaterials.

Further, there exists a clear need for improved, cost-effectivedeposition targets comprising recycled Ru and Ru-based alloy materials.

SUMMARY

In one aspect, an advantage of the present disclosure is an improvedmethod of recycling ruthenium (Ru) and Ru-based alloys.

In one aspect, another advantage of the present disclosure is animproved method of forming Ru and Ru-based alloy deposition sources,e.g., sputtering targets, from spent sources.

In one aspect, yet another advantage of the present disclosure isimproved Ru and Ru-based alloy deposition sources, e.g., sputteringtargets, fabricated from Ru and Ru-based alloy powders derived fromspent deposition sources.

Additional advantages and features of the present disclosure will be setforth in the disclosure which follows and in part will become apparentto those having ordinary skill in the art upon examination of thefollowing or may be learned from the practice of the present disclosure.The advantages may be realized and obtained as particularly pointed outin the appended claims.

According to an aspect of the present disclosure, the foregoing andother advantages are achieved in part by an improved method of recyclingruthenium (Ru) and Ru-based alloys, comprising steps of:

-   -   (a) providing a solid body of Ru or a Ru-based alloy;    -   (b) segmenting the solid body to form a particulate material;    -   (c) removing contaminants, including iron (Fe), from the        particulate material;    -   (d) reducing the particle sizes of the particulate material to        form a powder material;    -   (e) removing contaminants, including Fe, from the powder        material;    -   (f) reducing oxygen content of the powder material to below a        predetermined level to form a purified powder material; and    -   (g) removing particles greater than a predetermined size from        the purified powder material.

According to embodiments of the present disclosure, step (a) comprisesproviding a solid body in the form of a spent deposition source, e.g., asputtering target, and the method further comprises a step of:

-   -   (h) forming a deposition source, e.g., a sputtering target, from        the purified powder material.

Embodiments of the present disclosure include those wherein step (h)comprises consolidating the purified powder to have a tap density >˜5gm/cm³; and step (h) comprises hot isostatic pressing (“HIP”), vacuumhot pressing, or spark plasma sintering, and optionally furthercomprises cold isostatic pressing (“CIP”).

Further embodiments of the present disclosure include those wherein step(h) comprises addition of a predetermined amount of at least one elementto the purified powder prior to consolidating, e.g., as when step (a)comprises providing a solid body of a RuCr alloy; and step (h) comprisesadding a predetermined amount of chromium (Cr) to the purified powder.

According to embodiments of the present disclosure, step (b) comprisesoptional jaw crushing followed by hammer milling; step (c) comprises afirst leaching to remove iron (Fe) and other contaminants, followed bydrying; step (d) comprises impact milling; step (e) comprises a secondleaching to reduce Fe content to <˜500 ppm and remove othercontaminants, followed by drying, and further comprises performing amagnetic separation to remove Fe prior to the second leaching; step (f)comprises reducing oxygen content to <˜500 ppm, as by performing areduction process in an atmosphere containing hydrogen gas and annealingthe purified powder material during the reduction process.

In one aspect, preferably, step (e) comprises reducing Fe content to<˜500 ppm; and step (f) comprises reducing oxygen content <˜500 ppm.

Another aspect of the present disclosure is recycled Ru or Ru-basedalloys made by the above process, e.g., powder materials having adesired mesh size, e.g., 325 mesh, and tap density >˜5 gm/cm³.

Still another aspect of the subject technology is Ru and Ru alloy-baseddeposition sources, e.g., Ru and RuCr sputtering targets, fabricatedfrom the powder material formed by the above process, with densitiescomparable to those of Ru and Ru-based sources/targets fabricated fromvirgin Ru and RuCr powder material and hardness greater than those of Ruand Ru-based sources/targets fabricated from virgin Ru and RuCr powdermaterial.

Additional advantages and aspects of the present disclosure will becomereadily apparent to those skilled in the art from the following detaileddescription, wherein only the preferred embodiments of the presentdisclosure are shown and described, simply by way of illustration of thebest mode contemplated for practicing the present disclosure. As will berealized, the disclosure is capable of other and different embodiments,and its several details are capable of modification in various obviousrespects, all without departing from the spirit of the presentdisclosure. Accordingly, the drawing and description are to be regardedas illustrative in nature, and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWING

The following detailed description of the embodiments of the presentdisclosure can best be understood when read in conjunction with thefollowing drawing, in which:

FIG. 1 is a flow chart schematically showing an illustrative, butnon-limitative embodiment according to the present disclosure.

DETAILED DESCRIPTION

In one aspect, the subject technology addresses and effectively solves,or at least mitigates, several problems and/or disadvantages associatedwith conventional chemical-based methodology for recyclingproducts/apparatus containing Ru and Ru-based alloy materials, e.g.,thin film deposition sources such as sputtering targets, and is basedupon discovery that recovery/recycling of Ru and Ru-based alloymaterials can be formed in an efficient, cost-effective manner whichsubstantially reduces the processing interval.

More specifically, in one aspect, the presently disclosed methodologyovercomes the following disadvantages associated with conventionalchemical refining processing for Ru recovery/recycling, including thehigh cost; extremely long processing intervals, e.g., on the order ofabout 12 weeks; the porous and highly agglomerated nature of therecycled product, rendering it undesirable for use in subsequentfabrication of new deposition sources, such as sputtering targets; andthe relatively low tap density of the recycled product powder, i.e.,about 4.0 gm/cm³ on average, necessitating increase in the packingdensity prior to target formation.

The improved methodology for Ru recovery/recycling will now be describedin detail with reference to FIG. 1, which is a flow chart schematicallyshowing an illustrative, but non-limitative, embodiment according to thepresent disclosure wherein spent sputtering targets are subjected to arecycling process for recovering high purity Ru and Ru-based alloymaterials for re-use in the manufacture of new sputtering targets.

In a first step according to the process methodology, a solid body of Ruor Ru-based alloy material, i.e., a spent sputtering target is providedand mechanically segmented into appropriately sized particles,illustratively 1 mm (˜0.04 in) pieces. Mechanical segmentation may, ifdesired, be accomplished via a 2-stage process comprising an initial jawcrushing step to form pieces in the 30-50 mm (˜1-2 in.) size range,followed by hammer milling to form smaller pieces in the 1 mm (˜0.04 in)size range.

According to the next step of the process methodology, the smallerpieces are subjected to a first leaching, e.g., with a strong mineralacid such as hydrochloric (HCl) or nitric (HNO₃) acid, at roomtemperature for from about 12 to about 48 hrs., in order to removecontaminants from the pieces, especially any iron (Fe) introduced duringthe segmentation process. The leached particles are then subjected to afirst oven drying, and impact milled to form a powder material withabout 325 mesh size.

The powder material is then subjected to a second leaching, e.g., with astrong mineral acid such as hydrochloric (HCl) or nitric (HNO₃) acid, atroom temperature for from about 12 to about 48 hrs., to further removecontaminants, followed by a second oven drying. The Fe content of thedried powder after the second leaching should be very low, i.e., <500ppm, in order to prevent, or at least limit, diffusion of any Fe presenton the surfaces of the powder particles into the interior thereof duringsubsequent processing, e.g., hydrogen reduction. In this regard, itshould be recognized that any Fe present in the interior of the powderparticles is difficult to remove, e.g., by leaching.

According to the next step of the instant process methodology, the driedpowder from the second leaching step is subjected to reduction in ahydrogen (H₂) gas atmosphere at about 1,000° C. for about 12 hrs., toreduce oxygen content of the powder to below a desired level, typically<500 ppm. An advantageous feature of the present methodology annealingof the powder during the hydrogen reduction process, whereby any workhardening of the material incurred during the earlier segmentationprocessing is reduced. The feature of annealing during hydrogenreduction is critical for facilitating subsequent consolidation of therecycled powder.

The resultant purified powder is then sieved through a mesh screen,e.g., 325 mesh, to remove oversize particles and yield purified recycledRu or Ru-based alloy powder material.

The purified recycled Ru or Ru-based alloy material can be utilized,inter alia, for making Ru and Ru-based alloy deposition sources, e.g.,sputtering targets. In the case of recycled RuCr powder, Cr may be addedthereto according to the desired final composition of the depositionsource.

According to methodology afforded by the instant disclosure, therecycled purified Ru or Ru-based alloy powder is subjected toconsolidation processing, which may include optional CIP followed byHIP, vacuum hot pressing, or spark plasma sintering to achieve fulldensity. In this regard, whereas CIP is required for chemically recycledRu or Ru-based alloy powder because of its low tap density (<5 gm/cm³),CIP of recycled Ru or Ru-based alloy powder formed according to thepresent methodology is not necessarily required in view of its highertap density (>5 gm/cm³).

Ru and Ru alloy-based deposition sources, e.g., Ru and RuCr sputteringtargets, fabricated from the powder material formed by the above processby conventional powder metallurgical techniques, have densitiescomparable to those of Ru and Ru-based sources/targets fabricated fromvirgin Ru and RuCr powder material and hardness greater than those of Ruand Ru-based sources/targets fabricated from virgin Ru and RuCr powdermaterial.

Recycled Ru and Ru-based alloys, and products fabricated therefrom, suchas deposition sources (e.g., sputtering targets), have reduced Fecontent of <˜500 ppm and reduced oxygen content <˜500 ppm.

In one aspect, advantages afforded by the present methodology include:

-   -   1. the total recycling time is about 2 weeks, which is only        about 17% of the recycling time required by the conventional        chemical recycling process (i.e., about 12 weeks);    -   2. recycling cost is significantly less expensive than that of        the conventional chemical recycling process;    -   3. the recycled powder is non-porous and not agglomerated,        whereas the recycled powder produced by the conventional        chemical recycling process is porous and highly agglomerated. In        this regard, agglomerated powder is not preferred for use in        deposition source (e.g., sputtering target) manufacture via        powder metallurgical techniques; and    -   4. The recycled powder produced by the present process has a        high average tap density >˜5 gm/cm³ (as compared with an average        tap density of only about 4 gm/cm³ with powder produced via        conventional chemical recycling), thereby facilitating formation        of deposition sources via powder metallurgical techniques not        requiring a CIP step to increase tap density. As a consequence,        the present methodology affords further cost and processing time        reductions.

In the previous description, numerous specific details are set forth,such as specific materials, structures, processes, etc., in order toprovide a better understanding of the subject technology. However, thesubject technology can be practiced without resorting to the detailsspecifically set forth herein. In other instances, well-known processingtechniques and structures have not been described in order not tounnecessarily obscure the subject technology.

Examples of embodiments of the subject technology with variousversatility are shown and described in the present disclosure. It is tobe understood that the subject technology is capable of use in variousother combinations and environments and is susceptible of changes and/ormodifications within the scope of the inventive concept as expressedherein.

1. A recycled deposition source comprising ruthenium (Ru) or Ru-basedalloy material in the form of a powder material having a size notgreater than a 325 mesh size and having an average tap density greaterthan about 5 gm/cm³.
 2. The recycled deposition source of claim 1,wherein the powder material is non-porous, wherein the powder materialis not agglomerated, wherein the recycled deposition source comprisesless than about 500 ppm of iron (Fe) and less than about 500 ppm ofoxygen, wherein the recycled deposition source is a recycled Ru or RuCrdeposition source, wherein the recycled Ru or RuCr deposition source hasa density comparable to a density of a Ru or RuCr deposition sourcefabricated from virgin Ru or RuCr powder material, respectively, whereinthe recycled Ru or RuCr deposition source has a hardness greater than ahardness of a Ru or RuCr deposition source fabricated from virgin Ru orRuCr powder material, respectively.
 3. The recycled deposition source ofclaim 1, wherein the powder material is non-porous.
 4. The recycleddeposition source of claim 1, wherein the powder material is notagglomerated.
 5. The recycled deposition source of claim 1, wherein therecycled deposition source comprises less than about 500 ppm of iron(Fe) and less than about 500 ppm of oxygen.
 6. The recycled depositionsource of claim 1, wherein the recycled deposition source is a recycledRu deposition source, wherein the recycled Ru deposition source has adensity comparable to a density of a Ru deposition source fabricatedfrom virgin Ru powder material, wherein the recycled Ru depositionsource has a hardness greater than a hardness of a Ru deposition sourcefabricated from virgin Ru powder material.
 7. The recycled depositionsource of claim 1, wherein the recycled deposition source is a recycledruthenium-chromium (RuCr) deposition source, wherein the recycled RuCrdeposition source has a density comparable to a density of a RuCrdeposition source fabricated from virgin RuCr powder material, whereinthe recycled RuCr deposition source has a hardness greater than ahardness of a RuCr deposition source fabricated from virgin RuCr powdermaterial.
 8. The recycled deposition source of claim 1, wherein therecycled deposition source is in the form of a sputtering target.
 9. Therecycled deposition source of claim 2, wherein the recycled depositionsource is in the form of a sputtering target.
 10. The recycleddeposition source of claim 3, wherein the recycled deposition source isin the form of a sputtering target.
 11. The recycled deposition sourceof claim 4, wherein the recycled deposition source is in the form of asputtering target.
 12. The recycled deposition source of claim 3,wherein the powder material is not agglomerated.
 13. The recycleddeposition source of claim 3, wherein the powder material is notagglomerated, wherein the recycled deposition source comprises less thanabout 500 ppm of Fe and less than about 500 ppm of oxygen.
 14. Therecycled deposition source of claim 12, wherein the recycled depositionsource is a recycled Ru deposition source, wherein the recycled Rudeposition source has a density comparable to a density of a Rudeposition source fabricated from virgin Ru powder material, wherein therecycled Ru deposition source has a hardness greater than a hardness ofa Ru deposition source fabricated from virgin Ru powder material. 15.The recycled deposition source of claim 12, wherein the recycleddeposition source is a recycled ruthenium-chromium (RuCr) depositionsource, wherein the recycled RuCr deposition source has a densitycomparable to a density of a RuCr deposition source fabricated fromvirgin RuCr powder material, wherein the recycled RuCr deposition sourcehas a hardness greater than a hardness of a RuCr deposition sourcefabricated from virgin RuCr powder material.
 16. The recycled depositionsource of claim 13, wherein the recycled deposition source is a recycledRu deposition source, wherein the recycled Ru deposition source has adensity comparable to a density of a Ru deposition source fabricatedfrom virgin Ru powder material, wherein the recycled Ru depositionsource has a hardness greater than a hardness of a Ru deposition sourcefabricated from virgin Ru powder material.
 17. The recycled depositionsource of claim 13, wherein the recycled deposition source is a recycledruthenium-chromium (RuCr) deposition source, wherein the recycled RuCrdeposition source has a density comparable to a density of a RuCrdeposition source fabricated from virgin RuCr powder material, whereinthe recycled RuCr deposition source has a hardness greater than ahardness of a RuCr deposition source fabricated from virgin RuCr powdermaterial.
 18. The recycled deposition source of claim 1, wherein therecycled deposition source comprises less than about 500 ppm of oxygen,wherein the recycled deposition source is formed using a methodcomprising: providing a solid body of Ru or Ru-based alloy material;segmenting the solid body to form a particulate material; removingcontaminants, including Fe, from the particulate material; reducingparticle sizes of the particulate material to form a reduced powdermaterial; removing contaminants, including Fe, from the reduced powdermaterial; reducing oxygen content of the reduced powder material to forma purified powder material; and removing particles greater than apredetermined size from the purified powder material.
 19. The recycleddeposition source of claim 17, wherein the recycled deposition sourcecomprises less than about 500 ppm of Fe, wherein the solid body is inthe form of a spent deposition source.
 20. The recycled depositionsource of claim 18, wherein the spent deposition source comprises asputtering target, and wherein the Ru-based alloy material comprises Cr.